That is the port/connecter type, not your DATA rate.
Router and wireless network adapters are all 802.11 protocal.
But there are different levels or variations of the protocol
The oldest and slowest is a, the newest and fastest is n+.
You have a fast router. If you match it to a fast wireless adapter, you can get it's full wireless data rate.
But a router with 802.11 a is just as fast as a router with 802.11 n when you are connecting your computer to it with a network cable.